Remove last traces of qextserial from rpm

Author: daniviga

rpm/qgis.spec.template

@@ -96,7 +96,7 @@ BuildRequires: qt5-qttools-static
 BuildRequires: qt5-qtwebkit-devel
 BuildRequires: qt5-qtxmlpatterns-devel
 BuildRequires: qtkeychain-qt5-devel
-BuildRequires: qextserialport-devel
+BuildRequires: qt5-qtserialport-devel
 BuildRequires: qt5-qt3d-devel
 
 # Qwt stuff